Tamper-proof closure with plastic liner

ABSTRACT

A TAMPER-PROOF CLOSURE WITH A PLASTIC LINER AND METHOD TO FABRICATE SAME. A HEAT SHRINKABLE PLASTIC LINER WITH AN OPTIONAL TAMPER-PROOF BAND REGION IS SHRUNK ABOUT THE THREADED PORTION OF A CONTAINER. AFTER THE CONTAINER IS FILLED WITH THE DESIRED PRODUCT, A METAL SHELL IS TELESCOPED OVER SAID LINER AND BONDED TO THE LINER OPPOSITE THE THREADED AREA. THE SHELL AND LINER ARE REMOVED BY ROTATION WITH THE OIPTIONAL TAMPERPROOF BAND ADHERING TO THE NECK OF THE CONTAINER.

United States Patent lnventor John D. Northup Toledo, Ohio 778,256

Nov. 22, 1968 June 28, 1971 Owens-Illinois, Inc.

AppL No. Filed Patented Assignee TAMPER-PROOF CLOSURE WITH PLASTIC LINER9 Claims, 4 Drawing Figs.

Int. Cl .i B65d 23/00, 865d 53/00 Field of Search 215140, 38 (A); 229/43[56] References Cited UNITED STATES PATENTS 3,402,874 9/1968 Sternau v.2 l 5/38-(AX) 3,417,539 12/1968 l-lirohama 215/38(X) FOREIGN PATENTS678,389 1/1964 Canada 215/38 Primary Examiner-George T. Hall Attorneys-Philip M. Rice and E. J. Holler ABSTRACT: A tamper-proof closure with aplastic liner and method to fabricate same. A heat shrinkable plasticliner with an optional tamper-proof band region is shrunk about thethreaded portion of a container. After the container is filled with thedesired product, a metal shell is telescoped over said liner and bondedto the liner opposite the threaded area The shell and liner are removedby rotation with the optional tamper-proof band adhering to the neck ofthe container.

PATENTEBJUH28|971 8587.888

INVENTUR; JOHN D. NORTHUP 624% M; 6PM fyfeh ATroRmevS TAMPER-PROOFCLOSURE WITH PLASTIC LINER THE INVENTION This invention relates to anovel closure assembly and the method of forming the same. Moreparticularly, this invention relates to a cap closure to be applied to acontainer by first shrinking upon the finished threads a heat-deformableplastic liner, and then applying an adhesive coated metal cap to form aclosure which is tamper-proof, resistant to insect infestation, andeasily removed by rotation. If desired, the plastic liner may have atamper-proof band.

At the present time, there is a wide variety of cap closures currentlyin use which are designed to solve a multitudinous number of problemswhich are discussed below. One of these problems is insect infestation.

Insects lay eggs and larvae are commonly produced in the open spacewhich exists between the neck of a container and the lower edge of a capused to seal the container. When such a container is opened and anyvacuum is released thereby equalizing the internal pressure of thecontainer with the pressure of the atmosphere at the jar mouth, theinrushing air to the interior of the jar will pass by the regionoccupied by the insect larvae and cause some of the larvae to betransported into the container, causing contamination of the storedproduct.

Another problem relating to the design of closure is spillage. Whencontainers are being filled with baby food products, or the like, theyare frequently subjected to spillage of the food product onto theexterior threaded finish of the container. Upon later application of aclosure by automatic machine which is insensitive to the cleanliness ofthe glass, any such food product smears between the closure and theglass. This often freezes the closure onto the finish of the threads,making removal by the housewife virtually impossible. Even when the capis removed, the oxidized food product on the glass and cap is unsightly.

Creeping of the closure is also another problem. Minor deposits ofstannic chloride or the like resulting from surface treatment of theglass when deposited upon the finished surface of the glass causesclosures to slip or creep and loosen during handling of the filledcontainers subsequent to the processing of the food, thereby causingleaks and release of the vacuum. Food spoilage results.

In designing closure, it is desirable to consider the ease with whichthey can be applied to or removed from the container. From thestandpoint of application, a closure which requires only a straightdownward movement relative to the container is preferred over onerequiring a rotational movement to screw it on. The reason for this isthat such closures can be applied at a higher rate of speed and requireless complicated equipment than screw-on closures. On the other hand,from the standpoint of removal, it is preferred that the closure removalbe by a single unscrewing movement.

One form of closure cap presently exists which attempts to solve some ofthe problems heretofore illuminated. In this type of closure, thecontainer is first filled with the desired product and, subsequently,the container is sealed with a closure which has a plastic linerdeposited within it; The inherent disadvantage of this cap is that theplastic liner is applied to the container at the same time as theexterior cap members. Therefore, the cap does not solve the problem ofspillage and later freezing of the product on the surface of thefinished threads.

With these problems in mind, a closure was developed which could beapplied with the simplest type of capping equipment at high speeds andyet could be easily removed without the use of tools and reappliedwithout difficulty.

The present invention includes a combined sleeve gasket member liner ofshrinkable plastic applied over the finished threads and rim of a glasscontainer and a straight or tapered nonthreaded metal cap shelladhesively bonded to the plastic liner in situ during the retorting toform a composite closure.

More specifically, the present invention utilizes an elastomeric orplastomeric liner telescoped over the finished threads of a containerafter the container IS formed and inspected in the glass plant. Afterthe liner has been applied to the neck of the container. the containeris processed by heating it within a tunnel or oven of suitable type andtemperature to shrink the deformable plastic liner around the contoursof the threaded finish. The plastic is selected from available plasticmaterials which are easily formed on known molding equipment at highrates of production. Such plastic may be a heat reacting shrink-typepolyvinyl chloride.

The jar is now ready to be filled with the desired product. Any spillagewhich may result while the container is being filled will splash on theoutside of the preshrunk plastic liner and not on the threaded finish. Athin-walled metal shell which has been previously interiorly lined witha heat reactive adhesive material is pressed telescopically over theformed, shrunken liner or in the alternative, a thin-walled metal shellis pressed telescopically over a formed, shrunken liner which is coatedwith a heat reactive adhesive material so that the metal of the closureshell is tenaciously bonded to the preshrunk liner at contact pointsopposite the threads of the container finish and opposite the adjacenthorizontal surface of the rim portion of the neck of the container toform a one-piece integral cap.

One form of such a heat reactive adhesive suitable for bonding the metalshell to the plastic liner is a methyl methacrylate compound, an exampleof which is now shown.

Percent E oxy resin (Epon 1007) 16. 5 Methyl Methacrylate resin(Aeryloid A101) 7. 0 Diethylene triamine 0. 66 Methyl isobutyl ketone25. 4O Methyl ethyl ketone 50. 44

In the case of containers containing baby food products, the entirepackage is sent to a retort where it is soaked in heat in order toprocess the food. In the retort, the heat is sufficient to react theadhesive to bind the metal shell and the shrunken plastic liner at theabove-mentioned contact points. When the closure is used in conjunctionwith baby food products, it may be constructed with a domed orsnap-button diaphragm (center diaphragm) as is now commonly used inlug-type baby food metal closures. Such snap-button closure is disclosedin US. Pat. No. 3,142,711, which is assigned to the assignee of thepresent invention. The interior of the container, if closured properly,then draws a vacuum to depress the button on the top of the metal shell.

Upon opening the container, a twisting motion of the outside metal shellwill unscrew the plastic liner at the threads of the finish.

The torque necessary to remove the resulting cap and liner may becontrolled by lubricating the glass prior to the application of theplastic liner or by including lubricants in the shrinkable plasticcompound. Then, if food products are splashed onto the outside of theliner when the container is being filled or capped, the subsequenttorque required to remove the cap will not be affected by the freezingof the product to the liner since this removal torque is determined fromthe earlier established contact between the shrunken plastic liner andthe clean glass threads which occurred prior to filling. The package maybe rescaled by turning the composite metal shell and plastic liner ontothe jar finish.

A simple addition to the above-described closure assembly will alsoyield a closure which will solve the problem of tampering. It is anobservable practice on the part of many shoppers to remove closure capsfrom food-containing jars in a retail store, sample the products withtheir finger, smell the contents, reapply the closure cap and too oftenreturn the already opened and no longer sterile packages to the storeshelf for purchase by another unsuspecting customer. In order to helpeliminate this problem, a closure was developed which utilizesessentially the same combination of plastic liner and metal shellheretofore-described However, the skirt of the plastic liner IS extendedbelow the lower edge of the metal shell. In fonning the plastic liner. acircumferential or perforated score line is imposed at the lower part ofthe plastic skirt immediately below the lower edge of the metal shell.The interior surface of the plastic skirt below the score line may betreated with a heat reacting adhesive or in the alternative, theopposite annular recessed region of the glass neck below the neck finishmay be treated with such an adhesive such that after the plastic lineris shrunken onto the glass finish contour, the heat treatment of thecontainer will react the adhesive of the lower recessed neck region tobond that plastic band to the An example of such a heat-sensitiveadhesive suitable to bond the liner to the glass is the polyvinylacetate, polyvinyl alcohol type sold by the Borden Company under thetrademark Elmer's Glue." The chemical composition of Elmers Glue" isbelieved to be a liquid emulsion of the polymerized addition product ofacetylene and acetic acid, e.g., polyvinyl acetate.

Upon opening the container, a twisting motion of the metal shell willunscrew the plastic liner on the threads of the finish. The tamper-proofband region of the plastic liner below the score line will remainadhered to the glass and separate from the body of the liner along thescore line. Thus, the ultimate purchaser of the product can easilydetermine whether the jar has once been opened.

An advantage of these closures is that the liner may be supplied by thebottle manufacturer prior to shipment to the food processor. The linerserves to reduce chipping of the rim of the bottle in transit. After thebottle is filled by the processor with the desired product, the metalshell can be applied by the processor.

Keeping in mind the solution of the above-described problems, and thesolution of other problems which may be hereinafter disclosed, it is anobject of the present invention to provide a novel closure assemblywhich may be formed with simple equipment.

It is a further object of the present invention to provide a reusablecap closure which is sealed by forcing it downwardly on the containerwithout intentional rotation, but yet which can be easily removed byrotation.

It is an additional object of the present invention to provide a capconstruction having a seal which prevents infestation of mold or insectsbetween the cap and the container.

It is another object of this invention to provide a closure which willnot slip or creep during handling, subsequent to processing the food,thereby causing leaks and releasing any vacuum formed in the container.

It is a still further object of the preset invention to provide aclosure assembly having a shrunken plastic liner formed over thecontours of the finished threads, and a metal shell telescoped over saidliner, such that any spillage of the food product will lodge on theplastic liner rather than on the bare glass surface of the threads,thereby facilitating subsequent removal of the composite metal shell andliner from the container.

Another object of the present invention is to provide a tamper-proofclosure with a tamper-proof band region in the plastic liner separatedby a score line to visibly indicate whether a jar, or such container,has been tampered with or subjected to unauthorized breaking of theoriginal hermetic seal.

Still another object of the present invention is to provide a new andimproved method of forming a closure assembly by first applying ashrinkable plastic liner over the finished threads and rim of a glasscontainer, and then applying telescopically a straight or taperednonthreaded metal cap which is adhesively bonded to the plastic liner insitu during retortation to form a composite closure.

An object of the present invention is to provide a method of forming atamper-proof closure assembly by first applying a shrinkable plasticliner which has been circumferentially perforated with a scoreline andadhesively bonded to the glass below the scoreline and addingtelescopically thereto a straight or tapered non-threaded metal capwhich is adhesively bonded to the plastic liner in situ duringretortation to form a composite closure.

Also, an object of the present invention is to provide a method offilling and sealing a container by applying a shrinkable plastic liner,with an aperture in the top portion thereof, over the finished threadsand rim of a glass container; filling said container through saidaperture with the desired product; and then applying telescopically astraight or tapered nonthreaded metal cap which is adhesively bonded tothe plastic liner in situ during retortation to form a compositeclosure.

The attainment of the above, and further objects of the presentinvention will be apparent from the following specification taken inconjunction with the accompanying drawing forming a part thereof:

IN THE DRAWINGS FIG. 1 is a fragmentary sectional view of a containerwith the sleeve gasket plastic liner, and an optional tamper-proof bandapplied prior to heat processing.

FIG. 2 is a view similar to FIG. 1 showing the liner after heatshrinking it into conformity with the threaded finish.

FIG. 3 is a fragmentary sectional view of a container with a deformableplastic liner, and a tamper-proof band heat shrunk over the finishedthreads of the container, and a metal shell superimposed upon theplastic liner.

FIG. 4 is a fragmentary sectional view of the container and a closure ofFIG. 3, but without the tamper-proof band.

Referring now, in more detail and by reference numerals, to the drawingswhich illustrate a preferred embodiment of the present invention, thereis provided a container 10 having a neck portion with helical threads 11on the outer surface thereof. The neck has an interior wall 17 andterminates at its upper end in an annular rim 18. A preformedheat-deformable plastic liner 12 is superimposed upon the container 10and has a cylindrical skirt 14 with an optional circumferentialscoreline or perforated tear line 19 at a lower part of the skirt and anannular rim gasket portion 15 is joined at a corner radius 16.

The annular rim gasket 15 of liner 12 is in contact with the containerrim 18 and extends radially inwardly to a point generally aligned withthe interior wall 17 of the container. Such construction permits thecontainer to be later filled with food products prior to the applicationof metal shell 23.

If a tamper-proof band is not desired, the preformed plastic liner issevered along the same circumferential line that would have formed thescore line. However, if the tamper-proof feature is desired, theinterior surface 20 of skirt 14 below scoreline 19 is treated with aheat reacting adhesive or in the alternative, the opposite annularrecessed region 22 of the glass container below the neck finish istreated with an adhesive such that after liner 12 is shrunken onto theglass finish contour, the heat treatment of the container will react theadhesive to bond the plastic band to container 10 at recessed region 22below the scoreline.

After a glass container has been formed in a glass plant, annealed andlined in single order through inspection equipment, it passes anassembly point whereat plastic liners 12 are placed over the jar finish.The liner is positioned such that the annular rim gasket portion 15 ofliner 12 contacts container rim 18 while cylindrical skirt 14 contactshelical threads 11 at the outermost points thereof.

Then the container and the preformed plastic liner is passed through aheating process where the plastic liner is shrunk to conform to thecontours of the glass finish and straight skirt 14 is transformed intomolded skirt 14', as shown in FIG. 2.

FIG. 2, similar to FIG. 1, shows the plastic liner after it has beenheat shrunk to conform with the threaded finish. Plastic liner 12 istransformed to shrunken liner 12'; liner skirt 14 is transformed toshrunken skirt l4; rim gasket 15 is transformed to shrunken gasket 15;etc. The container is filled with the desired food product, and a metalshell 23 is telescoped over the container and the fitted liner to form acomposite closure as shown in H65. 3 and 4.

FIG. 4 illustrates a composite closure which is formed by telescoping anomthreaded metal shell 23 over container and shrunken plastic liner 12.The metal shell is characterized by a cylindrical skirt 24 which may beeither straight or tapered, and a top panel 28 completely covering theopening to the container joined to the skirt at comer radius 30. Whenthe metal shell is superimposed upon shrunken plastic liner l2 to sealthe container, the shell is tenaciously bonded to the deformed liner atcontact points 26 and 27, opposite the outermost points of helicalthreads 11 of the jar finish and at the point opposite the adjacentsurface of rim gasket portion 15. Such bonding is effected by the actionof heating the package in the area of the heat-reactive adhesivematerial which has been applied either to the interior of the metalshell or in the alternative to the exterior of shrunken liner.

If, as shown in FIG. 3, the composite closure includes a tamper-proofband, the edge 25 of metal shell 23 is not extended below scoreline 19so that the scoreline is visible for easy detection.

When opening the container, a twisting motion of metal shell 23 willunscrew plastic liner l4 deformed upon threads 11 of the glass finish.When a tamper-proof closure is provided, the tamper-proof band region 22of skirt 14' below scoreline 19 will adhere to the glass and separatefrom the body of liner 12 along scoreline 19.

The container may be resealed by turning the composite of liner l2 andmetal shell 23 on the jar finish.

It can be seen from the foregoing that the present invention provides anovel reusable closure assembly which can be easily applied to acontainer, and which eliminates the problems of insect infestation,slipping or creeping of the closure cap, and spillage and subsequentfreezing of the closure to the finished threads. With these and otherproblems in mind which may be disclosed, it it understood that theforegoing is a description of preferred embodiments of the invention,and that various modifications may be made without departing from itsspirit and scope.

lclaim:

l. A package comprising in combination a container having a neck portionand a rim portion and a closure assembly which includes a plastic linerof substantially uniform thickness covering the rim portion of saidcontainer with an annular skirt extending axially from the mouth of thecontainer and conforming to the finish contour of the neck portionthereof, a shell telescoped upon said liner having a top panel portionand a cylindrical skirt extending axially from the top panel, said shellcontacting the liner skirt only at a plurality of contact points locatedaround the rim of said container, and means to bond said shell to saidliner at the contact points on the finish of the neck of the container.

2. The combination as claimed in claim 1 wherein the closure assemblyincludes a plastic liner covering the rim portion of the container,which liner has an aperture therein allowing said container to be filledprior to the application of the telescoped shell.

3. The combination as claimed in claim 2 wherein the aperture withinsaid liner consists of an annular opening, the edge of which isgenerally aligned with the interior wall of the rim of the container.

4. A package comprising in combination a container having a threadedneck portion and a rim portion, and a closure assembly which includes aliner of substantially uniform thickness with a top thereon covering therim portion of said container, and an annular skirt extending axiallyfrom the mouth of the container and conforming to the contour of thefinish of the threaded neck portion thereof, a shell telescoped uponsaid liner having a top panel portion and a cylindrical skirt extendingaxially from the top panel, said shell contacting the liner skirt onlyat the crest of the threads, and means to bond said shell to said linerat the threaded neck portion of said container.

5. The combination as claimed in claim 4 wherein said liner comprises aheat-shrinkable plastic material.

6. The combination as claimed in claim 5 wherein the top of the linercovering the rim portion of the container includes an aperture thereinallowing said container to be filled prior to the appllicationpf thetelescoped shell.

7. e combination as claimed in claim 6 wherein the aperture within saidliner consists of an annular opening, the edge of which is generallyaligned with the interior wall of the rim of the container.

8. The combination as claimed in claim 5, wherein the annular skirt ofthe liner includes a scoreline or perforated tear line below the loweredge of the skirt of the shell, and means to bond that portion of saidliner below the scoreline or perforated tear line to the container sothat upon application of a twisting torque to said shell, the portion ofthe liner below the scoreline or perforated tear line will adhere to thecontainer.

9. The combination as claimed in claim 4 wherein the bonding meansconsists of a heat-reactive adhesive applied between the telescopedshell and the liner so that the liner will adhere to the shell uponapplication of a twisting torque to said shell.

